Oligomerization of the Macrophage Mannose Receptor Enhances gp120-mediated Binding of HIV-1
Oligomerization of the Macrophage Mannose Receptor Enhances gp120-mediated Binding of HIV-1
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DOI：
10.1074/jbc.m809698200
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发表时间：
2009-04-24
影响因子：
4.8
通讯作者：
Cunningham, Anthony L.
中科院分区：
文献类型：
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作者：
Lai, Joey;Bernhard, Oliver K.;Cunningham, Anthony L.
树突状细胞和巨噬细胞表面表达的C型凝集素受体能够通过甘露糖、岩藻糖和N-乙酰葡糖胺结合微生物病原体的糖蛋白。朗格汉斯细胞上的郎格蛋白、树突细胞上的树突细胞特异性细胞间粘附分子3-抓取非整联蛋白以及树突细胞和巨噬细胞上的甘露糖受体（MR）主要通过高甘露糖寡糖结合人类免疫缺陷病毒（HIV）包膜蛋白gp 120。这些C型凝集素受体也可以寡聚化以促进增强的配体结合。本研究检测了MR寡聚化对其与甘露聚糖、单体gp 120、天然三聚体gp 140和HIV 1型BaL结合能力的影响。交联MR的质谱分析显示，在原代单核细胞衍生的树突状细胞和巨噬细胞的表面上均二聚化。单体和二聚体的MR沉淀甘露聚糖，但只有二聚体形式的gp 120免疫共沉淀。这些结果通过可溶性单体和三聚体HIV包膜的流式细胞术分析和细胞HIV病毒体捕获测定独立地证实。正如预期的那样，甘露聚糖结合的碳水化合物识别结构域的MR二聚体主要是在钙依赖性的方式。出乎意料的是，gp 120介导的结合的HIV二聚体的MR转染的大鼠-6细胞和巨噬细胞是不依赖于钙，只有部分被甘露聚糖阻断，也部分抑制N-乙酰半乳糖胺4-硫酸盐。因此，gp 120介导的HIV结合通过钙依赖性、非钙依赖性碳水化合物识别结构域和MR二聚体C末端的富半胱氨酸结构域发生，为gp 120-MR结合的潜在抑制剂提供了更广泛的靶点。
C-type lectin receptors expressed on the surface of dendritic cells and macrophages are able to bind glycoproteins of microbial pathogens via mannose, fucose, and N-acetylglucosamine. Langerin on Langerhans cells, dendritic cell-specific intercellular adhesion molecule 3-grabbing nonintegrin on dendritic cells, and mannose receptor (MR) on dendritic cells and macrophages bind the human immunodeficiency virus (HIV) envelope protein gp120 principally via high mannose oligosaccharides. These C-type lectin receptors can also oligomerize to facilitate enhanced ligand binding. This study examined the effect of oligomerization of MR on its ability to bind to mannan, monomeric gp120, native trimeric gp140, and HIV type 1 BaL. Mass spectrometry analysis of crosslinked MR showed homodimerization on the surface of primary monocyte-derived dendritic cells and macrophages. Both monomeric and dimeric MR were precipitated by mannan, but only the dimeric form was co-immunoprecipitated by gp120. These results were confirmed independently by flow cytometry analysis of soluble monomeric and trimeric HIV envelope and a cellular HIV virion capture assay. As expected, mannan bound to the carbohydrate recognition domains of MR dimers mostly in a calcium-dependent fashion. Unexpectedly, gp120-mediated binding of HIV to dimers on MR-transfected Rat-6 cells and macrophages was not calcium-dependent, was only partially blocked by mannan, and was also partially inhibited by N-acetylgalactosamine 4-sulfate. Thus gp120-mediated HIV binding occurs via the calcium-dependent, non-calcium-dependent carbohydrate recognition domains and the cysteine-rich domain at the C terminus of MR dimers, presenting a much broader target for potential inhibitors of gp120-MR binding.